The invention relates to improvements in liners for the internal surfaces of water mains, pipes which branch off water mains, sewage lines and/or other types of conduits which are not readily accessible. More particularly, the invention relates to improvements in liners for the internal surfaces of pipes including those which are accessible at a single location, e.g., at one end.
It is already known to provide the internal surface of a pipe with a liner (e.g., to seal a leak in the pipe) which contains a hardenable resin-permeated substrate adapted to be inverted into a pipe and to be thereupon caused or permitted to harden as a result of setting of the resin. A drawback of heretofore known proposals is that the pipe which is to be repaired must be accessible at two spaced-apart locations. This creates many problems and contributes to the cost of the repair work because a second access to the pipe must be established for the sole purpose of introducing the liner into a damaged portion of the pipe. The resin-impregnated substrates which are used for such proposals are known as softliners. A softliner is a flexible tube of fibrous material which is permeated with a suitable resin and the tube can be introduced into a damaged pipe by resorting to a winch or by inversion. The inserted pipe is thereupon heated (e.g., as a result of exposure to ultraviolet radiation, ambient temperature or exchange of heat with a hot fluid) so that the resin sets and the outerside of the hardened liner closely follows the internal surface of the pipe. The just outlined procedure cannot be relied upon in many instances when a pipe which is to be lined from the inside is accessible at a single location, e.g., at one end. This applies for nearly all branch lines of water mains and sewage pipes for delivery of fresh water into or for evacuation of sewage from private homes, apartment houses and numerous other establishments. Furthermore, this also embraces all types of pipes, lines, mains and other conduits having dead ends.